It is known to utilize various cryoprotectants, such as for example dimethyl sulfoxide, during cryopreservation of cells. Use of a cryoprotectant is essential to prevent cryoinjury from, e.g., formation of intracellular ice crystals during freezing. However, at room and/or body temperature, certain cryoprotectants such as DMSO are known to be toxic to cells. Accordingly, cryoprotectant must be removed from cryopreserved cell cultures as soon as possible after thawing to prevent cellular damage.
The most common method for removal of cryoprotectant from cryopreserved cells is by mechanical removal, i.e. centrifugation followed by resuspension in the media of choice to remove the cryoprotectant by dilution. However, the mechanical forces introduced during centrifugation result in osmotic stress and cell clumping/lysing, particularly if the cell of choice is fragile. The generally open nature of most centrifugation processes may also result in bacterial or viral contamination of cell preparations. Accordingly, there is need in the art for a method of removing cryoprotectant which does not result in cell damage or risk contamination of cell preparations. The instant invention satisfies this need by providing a method and device for removing cryoprotectant using a counter-current perfusion washing system.